#![allow(dead_code)]

use std::fmt;
use std::future::Future;
use std::pin::Pin;
use std::sync::Arc;

use hyper::rt::Executor;

pub(crate) type BoxSendFuture = Pin<Box<dyn Future<Output = ()> + Send>>;

// Either the user provides an executor for background tasks, or we use
// `tokio::spawn`.
#[derive(Clone)]
pub(crate) enum Exec {
	Executor(Arc<dyn Executor<BoxSendFuture> + Send + Sync>),
}

// ===== impl Exec =====

impl Exec {
	pub(crate) fn new<E>(inner: E) -> Self
	where
		E: Executor<BoxSendFuture> + Send + Sync + 'static,
	{
		Exec::Executor(Arc::new(inner))
	}

	pub(crate) fn execute<F>(&self, fut: F)
	where
		F: Future<Output = ()> + Send + 'static,
	{
		match *self {
			Exec::Executor(ref e) => {
				e.execute(Box::pin(fut));
			},
		}
	}
}

impl fmt::Debug for Exec {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
		f.debug_struct("Exec").finish()
	}
}

impl<F> hyper::rt::Executor<F> for Exec
where
	F: Future<Output = ()> + Send + 'static,
{
	fn execute(&self, fut: F) {
		Exec::execute(self, fut);
	}
}
